CVE-2020-27304: The CivetWeb web library does not validate uploaded filepaths when running on an OS other than Windows, when u

Q: How do I fix CVE-2020-27304?

civetweb: upgrade to 1.15; sinec infrastructure network services: upgrade to 1.0.1.1. Exact commands for each OS are on this page.

Q: Is CVE-2020-27304 being exploited?

CVE-2020-27304 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-27304 affect?

CVE-2020-27304 affects civetweb, sinec infrastructure network services. Severity is critical (CVSS 9.8). The CivetWeb web library does not validate uploaded filepaths when running on an OS other than Windows, when using the built-in HTTP form-based file upload mechanism, via the mg_handle_form_request API. Web applications that use the file up

Q: How urgent is CVE-2020-27304?

Priority 66/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADEUPGRADE

CVE-2020-27304 is a critical-severity flaw (CVSS 9.8) affecting civetweb, sinec infrastructure network services. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The CivetWeb web library does not validate uploaded filepaths when running on an OS other than Windows, when using the built-in HTTP form-based file upload mechanism, via the mg_handle_form_request API. Web applications that use the file upload form handler, and use parts of the user-controlled filename in the output path, are susceptible to directory traversal

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.2% (top 12%)
CISA exploited list	No
Weakness	CWE-23, CWE-22
Published	2021-10-21
Last modified	2026-06-17

Publisher (CNA): VDOO Connected Trust Ltd. · Vendor: civetweb project · siemens

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-10-21 16:15 UTCPublished CVE record published
2026-06-17 03:09 UTCUpdated Record last modified

civetweb project civetweb UPGRADE

Affected: >= 1.8 and < 1.15

Fixed in: 1.15

Safe to downgrade to: a release before 1.8

1. Check installed version

apt-cache policy civetweb || rpm -q civetweb || civetweb --version

2. UPGRADE to 1.15 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade civetweb

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade civetweb

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.8 (Debian / Ubuntu)

apt-cache madison civetweb sudo apt install civetweb=<VERSION_BEFORE_1.8> sudo apt-mark hold civetweb

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list civetweb sudo dnf downgrade civetweb-<VERSION_BEFORE_1.8> sudo dnf versionlock add civetweb

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

siemens sinec infrastructure network services UPGRADE

Affected: < 1.0.1.1

Fixed in: 1.0.1.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy sinec-infrastructure-network-services || rpm -q sinec-infrastructure-network-services || sinec-infrastructure-network-services --version

2. UPGRADE to 1.0.1.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade sinec-infrastructure-network-services

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade sinec-infrastructure-network-services

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-27304?

civetweb: upgrade to 1.15; sinec infrastructure network services: upgrade to 1.0.1.1. Exact commands for each OS are on this page.

Is CVE-2020-27304 being exploited?

CVE-2020-27304 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-27304 affect?

CVE-2020-27304 affects civetweb, sinec infrastructure network services. Severity is critical (CVSS 9.8). The CivetWeb web library does not validate uploaded filepaths when running on an OS other than Windows, when using the built-in HTTP form-based file upload mechanism, via the mg_handle_form_request API. Web applications that use the file up

How urgent is CVE-2020-27304?

Priority 66/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Windows vulnerabilities · Siemens vulnerabilities

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References

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